Two White Dots on 56" DLP Samsung TV

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  #1  
Old 01-14-14, 12:48 PM
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Two White Dots on 56" DLP Samsung TV

I have a Samsung 56" DLP TV that is probaby 6 years old. It may have about 12,000 hours of use on it. The problem started a couple of days ago and consists of two small while dots that always appear in the exactly the same place on the screen. The larger one is about 1/16 inch by 1/8 inch. The smaller one is just a pinpoint. Naturally, they can only be seen when the screen is a dark color at that point.

Does anyone know what might be causing this slight problem. The TV works perfectly otherwise.
 
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Old 01-14-14, 07:28 PM
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Probably stuck pixels in the postage stamp sized picture generating element through which the projection lamp beam shines..

Ordinarily I would expect the white dots due to stuck pixels to all be the same size but perhaps the brighter spot is due to two pixels side by side both stuck.
 
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Old 01-15-14, 12:56 AM
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DLP works by reflection, not projection.

It's the same principle as stuck pixels. However, while stuck pixels in an LCD can usually be 'freed' through use of a pixel flipper in the panel's native resolution, white spots in a DLP are caused by dead pixel mirrors. This is due to burnout of the microscopic electromagnets that move the mirrors. The large dot is likely a cluster of burned out pixels, maybe caused by a power surge. You wouldn't normally see a bunch of them fail simultaneously like that without an outside force in play.

In order to create various light levels in DLP, the mirrors (one for each pixel) position themselves to direct some or all of the light from the color wheel either to the screen or into the 'light dump'. Since the 'parked' position is 'on', if the mirror isn't moving, it's always reflecting every color from the color wheel to the pixel. Result is that pixel displays converged RGB (because the color wheel spins faster than your eye can perceive) at full intensity.. White.

Being as it's out of warranty, you're SOL. The light engine can only be replaced as a unit, and the cost of replacing it (provided parts are available) will likely be far more than a current model TV of the same specs.
 

Last edited by taz420; 01-15-14 at 02:09 AM.
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Old 01-15-14, 07:10 AM
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Thank you for the information TAZ420 and AllanJ. Given the size of the screen and the fact that the picture is constantly changing when watching shows, we can live with the minute small white dots caused by mirrors stuck in the park position. If the tiny white specks are in a light color, we don't notice them.

So we'll continue enjoying the TV until it gets a lot worse. Are there any predictions regarding the length of time we have with it.
 
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Old 01-15-14, 04:32 PM
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One should normally expect at least 50,000 hours or more from the light engine (with bulb replacements of course). However since you're already experiencing issues, it would be tough to say when/if you'll have anymore mirrors burn out or when/if the entire chip might fail catastrophically.

Personally I would just take this as a cue to start saving a few bucks a week toward a new one.
 
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Old 01-15-14, 06:36 PM
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I should have said, "... picture generating element upon which the projector lamp beam shines ... ."
 
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